ROLEX REF. 16520 ZENITH DAYTONA STEEL Rolex, "Oyster Perpetual, Superlative Chronometer, Officially Certified, Cosmograph, Daytona," case No. U379631, Ref. 16520/16500. Made in 1997. Fine, self-winding, water-resistant, stainless steel wristwatch with round button chronograph, registers, tachometer and a stainless steel Oysterlock bracelet. Three-body, polished and brushed, screw-down case back, chronograph buttons and Triplock winding crown, tachometer graduation on the bezel to 400 units per hour, sapphire crystal. Bicolor white and black subsidiary dial rings, applied luminous white gold indexes, subsidiary dials for the seconds, the 12-hour and 30-minute registers, outer 1/5th seconds track. Luminous white gold baton hands. Cal. 4030, rhodium-plated, oeil-de-perdrix decoration, 31 jewels, straight-line lever escapement, monometallic balance adjusted to temperatures and 5 positions, shock absorber, self-compensating free-sprung Breguet balance spring, Microstella regulating screws.